1. Field of the Invention
The present invention relates to cephalosporin compounds represented by the general formual (I) and salts thereof and to processes producing them ##STR2## wherein A represents CH or N; R.sup.1 is a group represented by ##STR3## (wherein B is a single bond or a sulfur atom; and R.sup.3 is lower alkyl, pyridyl, thienyl, or a group of the formula ##STR4## (wherein R.sup.4 and R.sup.5 represent hydrogen atom or hydroxyl which may be protected)); R.sup.2 represents ##STR5## or --X--R.sup.6 (wherein X represents --CH.sub.2 O--, --CH.sub.2 --S--, --CH.dbd.CH-- or --CH.dbd.CH--S--; R.sup.6 represents (wherein R.sup.7 is hydrogen or lower alkyl), ##STR6## (wherein n is an integer of 1 to 5; R.sup.8 and R.sup.9 represent hydrogen or lower alkyl), ##STR7## (wherein R.sup.10 is hydrogen or lower alkyl), ##STR8## (wherein R.sup.11 is hydrogen, halogen, hydroxyl or lower alkoxy), ##STR9## (wherein R.sup.12 is hydrogen or lower alkyl), or ##STR10## (wherein R.sup.13 is hydrogen or a protective group for carboxyl) with the proviso that the following case is excluded A is CH, X is --CH.sub.2 --S--, R.sup.3 is ##STR11## B is a single bond, in combination.
2. Description of the Related Art (Prior Art and Subject to be Solved by the Invention)
The compounds of the present invention have antibacterial activity against a wide range of pathogens (gram positive and negative bacteria), and, in particular, show superior antibacterial activity against Pseudomonas aeruginosa.
According to the state of the art, are known many cephalosporin compounds having specific substituents at the 3- and 7- positions, as described in, for example, EP 197, 409.